“This is America, and to have a memorial service where there’s no prayer, this appears to be insanity to me,” said Mr. Washington, who has suffered severe medical problems connected to the time he spent at Ground Zero. “I feel like America has lost its way.”

City Hall officials, who are coordinating the ceremony, confirmed that spiritual leaders will not participate this year—just as has been the case during past events marking the anniversary. The mayor has said he wants the upcoming event to strike a similar tone as previous ceremonies.

“There are hundreds of important people that have offered to participate over the last nine years, but the focus remains on the families of the thousands who died on Sept. 11,” said Evelyn Erskine, a mayoral spokeswoman.

But the mayor’s plans this year have drawn increased scrutiny and some disapproval, as the event will attract an international audience and President Barack Obama will attend.

New Jersey Gov. Chris Christie has publicly criticized the mayor about the list of speakers, and New York Gov. Andrew Cuomo has quietly sought to play a larger role.

But the exclusion of religious leaders has struck some as particularly glaring.

City Council Member Fernando Cabrera, a pastor at New Life Outreach International, a Bronx church, said he is “utterly disappointed” and “shocked” by the event’s absence of clergy. When the terrorist attacks occurred, people in the city and nationwide turned to spiritual leaders for guidance, he said.

“This is one of the pillars that carried us through,” he said, referring to religious leaders. “They were the spiritual and emotional backbone, and when you have a situation where people are trying to find meaning, where something is bigger than them, when you have a crisis of this level, they often look to the clergy.”

Mr. Cabrera described the religious leaders’ exclusion as “wiping out the recognition of the importance that spirituality plays on that day.”

Rabbi Joseph Potasnik, executive vice president of the New York Board of Rabbis and one of the participants in the September 2001 interfaith ceremony at Yankee Stadium, said it would be difficult to include all faiths in the ceremony.

“I understand the feelings,” he said. “[But] I don’t know how we make it possible for everyone to have a place at the table.”

“Who’s going to agree as to who the representatives of the faith…will be? We have all the different groupings. If we have four denominations, what about the fifth denomination?” he said. “There are practical considerations when planning something, where you want to be as inclusive as possible but sometimes you find it impossible to have everyone present who should be present. It’s very difficult.”

A spokesman for Archbishop Timothy Dolan, the city’s most prominent religious leader, said he had no knowledge that Mr. Dolan had been invited. On Sept. 11, the archbishop plans to celebrate Mass at St. Patrick’s Cathedral in the morning, and later in the day he’ll be at St. Peter’s Church in Lower Manhattan.

Many religious institutions will be holding events to commemorate the anniversary. There will be an interfaith event recognizing first responders on Sept. 6.

During the 2001 “Prayer for America” service at Yankee Stadium, leaders from the major religions—Roman Catholics, Jews, Muslims, Hindus, Protestants, Sikhs, Greek Orthodox—addressed the crowd of thousands and an even larger TV audience from a podium atop second base.

“I brought every major religion to this event in Yankee Stadium,” said Mr. Washington, who is considering holding a news conference on Sept. 11 to object to the exclusion of clergy.